Piston



E. C. LEWIS June 13, 1933.

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Il lllllnl'l Patented June 13, 1933 UNITED STA-'rss ERIC CRISP LEWIS, OF STOKE, CGVENTRY, ENG-LAND rrsroiv Application filed November 21, 1932. Serial No. 643,l3.

This invention relates to pistons of the kind in which the joint between therpiston andthe connecting rod is of the ball and socket type. The object of the invention is to improve the construction of the joint so as to enable the piston to accommodate itself to the cylinder bore in a lateral direction relatively to the connecting rod without affecting the free `working of the joint.

The invention is particularly applicable to internal combustion engines where, in consequence of expansion of the cylinder block in a direction parallel with the crankshaft, there isa tendency for the cylinders to beL r come slightly deformed.

liiccordingl to this invention the pivotal centre of the joint is fixed in relation to the piston, provision being made for a limited degree of relative movement between the tion parallel with the aXis of the crank shaft.

Provision is also made for enabling the joint to withstand the severe stresses im posed Vupon it in service and to ensure an adequate supply of lubricant reaching the working faces of the joint.

In the accompanying drawing,

Figures l and 2 are sectional views ofthe improved joint taken in planes at right 3o-angles to each other.

Figures 3 and 4 are similar views illustrating a slight modification. f

Referring to the drawing, a represents the connecting rod and b the piston which can be die cast or forged in any suitable alloy with'an internal central pillar or tube b1 cast with or attached to the crown or skirt for the purpose of providing a means of attachment for the socket c of the ball and fso'cket joint. The end of the connecting rod is made with a head al which is flat in a plane at right angles to the longitudinal axis of the rod. The ball Z is divided into two sections in the same plane and, in order to enable the connecting rod and the said joint in a direc-V ball sections to be assembled, the lower part The contacting faces of the upper part of the ball and the flat head of the connecting` rod have a tongue and groove engagement a2 (Z3 along'a diameter parallel with the axis of the crank shaft so that a limited amount of relative movement between the ball al and rod a; is possible in this direction only. The ball sections may be made ofany suitable metal or material that will withstand the stresses `andwear to whichthey are subject in use. The said sections may, for example, be made of a composition of graphite and a noneferrous metal, such as copper, the two ingredients being mixed 'together in granular form' and subjected to high pressure in dies of the shape of the required sections. rifhis material combines the advantages of a hard wear resisting property with a porosity such as will allow lubricating` oil to percof late through it. i

T he socket c is made in upper and lower sections c, cl'of which the former takes a seating` in the pillar or tube El aforesaid whilst the lower section c1, which has a central hole c2 of a diameter suflicient to clear the head al of the connecting rod, is secured in position by means of a sleeve or collar c screwing into the end of the said pillar or tube and abutting against a lip 04 around the lower section o1 of the socket. This collar may either constitute a separate part, as shown in Figures 1 and 2, or may be formed as an integral part of the socket section c1 as represented in Figures 3 and ll. f y

lVhere the piston and collar are made .of metals having different coefficients of expansion, the co-acting screw threads are, as shown, of preferably square section so that, when relative movement takes place between them due to expansion there is less tendency for the collar to work loose, a portion, at least, of the flanks of the square threads on one part being always in contact with the flanks of the threads on the other part.

In order to enable tbc upper part of the socket c to withstand the severe tensional stresses to which it is subjected when the engine :is ruiming, it will be observed thatiin Figures l and 2 this part of they socket is strongly reinforced by means of an external iange c the thickness of which exceeds that of the wall of the socket c. This flange can be recessed around its external circumference, as shown, to reduce unnecessary weight. Alternatively, as shown in Figures 3 and 4 the plane of division between the upper and lower sections c, c1 of the socket instead of passing through the centre of the joint is off-set therefrom towards the crown of the piston thereby reducing the severity of the tensional stresses in the upper section of the socket.

Any suitable provision may be made for supplying the joint with lubricant, for example, the upper part of the ball l can bc bored through with an oil duct d* one end of which registers with an oil conduit f opening to the head of the connecting rod whilst the other end opens to a small cavity c3 in the socket- In this connection it will be observed that the groove (Z3, which receives the rib or tongue a2 on the flat end of the connecting rod and is formed in the upper section of the ball d, does not extend completely across the ball section but is closed at each end suiiicient clearance between it and the tongue being left for relative movement to take place between the joint and the connecting rod in a direction parallel with the axis of the crank-shaft. rlhe reason for forming the groove with closed ends is to make the joint oil-tight and prevent the lubricating oil from escaping between the parts of the ball instead of passing to the cavity c3 to feed the working surfaces of the ball and socket.

By means of this invention it will be seen that the piston is free to accommodate itself, not only to the Obliquity of the connecting rod, but to the cylinder also in so far as axial lignment of the latter with the crank may be adversely affected by longitudinal expansion of the cylinder block. Moreover, the piston being free to turn about the end of the connecting rod, the surface of the piston acting as a thrust face at any one cycle need not necessarily act as a thrust face on the next or any other cycle. rlhe adoption of the present invention also enables the piston wall to be made of a uniform and thinner section thereby avoiding any risk of distortion, and reducing weight. incidentally, it is computed that the improved piston will be less expensive, to manufacture than the y orthodox type fitted with gudgeon pins.

' groove extending through its plane face in a diametric direction with relation thereto and the other of said elements being formed with a centrally disposed rib fitting into said groove whereby relative rotary movement between said elements will be prevented, said rib being of such width and height as to make a snug lit in said groove and being of less length than said groove, whereby said female member together with said planospherical element may move bodily out of alignment with said male member.

2. A universal coupling comprising a female member and a male member, in combination with a plano-spherical block disposed in the socket of said female member and formed with an elongated groove extending through its plane face in a diametric direction with relation thereto, a plate rigidly connected to said male member and having a plane face engaging said plane Vface of said block, and a rib constituting the extreme end portion of said male member and extending into the groove in said block whereby relative rotary movement between said members will be prevented, said rib being of suoli width and height as to make a snug fit in said groeve and being of less length than said groove whereby said female member together with said block may move bodily out ef alignment with said male member.

3. A universal coupling comprising a female member and a male member, in combination with a plano-spherical block disposed in the socket of said female member and formed with an elongated groove extending through its plane face in a diainetric direc tion with relation thereto, said block being formed with a central lubricating bore eX- tending from its outer face into the adjacent portion of said slot, a head rigidly connected to said male member and having a plane face engaging said plane face of said block and a rib constituting the extreme end portion of said male member and extending into the groove in said block, whereby relative rotary movement between said members will be prevented, said rib being of such width and height as to make a snug lit in said groove and being of less length than said groove whereby said female member together with said block may move bodily ont of alignment with said male member, said male member being formed with a lubricating bore comniunicating with said slot and said plane face of said head being in all directions in said plane of greater length in diameter than the length of said slot, whereby the contact of said plane faces vill at all time seal the lubricant in said slot against escape between said plane faces.

ln testimony whereof, I have signed my name to this specification at Coventry, England, this 7 th day of November, 1932.

ERlC CRISP LEWIS. 

